1992 Yamaha 40 MSHQ lower water pump housing

[Douglasdzaster]

Hello again everyone. I’m back for more advice from the experts.
This also answered a previous post of mine with this experience.
I took my Monark 1652 out the other day and after 5 minutes at wot the engine shuts down and warning light came on. I’d forgotten to take my ir gun with me but it didn’t look like it was peeing right and the water felt to hot. It would idle fine but got hot if I wanted to throttle up. I shut it down as soon as I figured it was over heating and trolled back to the ramp. Got home and pulled the lower unit and sure enough the damper seal was pushed way up the pickup tube. There was no gasket above it like in the breakdown. Also the pump itself wasn’t tightened enough and was leaking from the gaskets . I ordered parts. May as well put a kit in while I’m here. Started cleaning the lower housing today and noticed it has some corrosion. Particularly around the shaft. I tried to remove it for cleaning but it wouldn’t budge. I’m thinking it’s the original housing . Should I leave well enough alone or take a chance damaging the lu to replace it? If I leave it I’ll probably need to apply a gasket dressing since it looks a little rough. I know if the oil seals start leaking later on I won’t have a choice.I’m going to try to post some pictures of it here. Any advice is greatly appreciated. Thanks https://tinboats.net/forum/download/file.php?mode=view&id=109933

 

[maintenanceguy]

I would wire brush what I can reach with a small brush and not worry too much about the rest. Just verify that the passages are clear, running in salt water for years can close up those passages.

I'd also use fine (200 grit) emory paper on the shaft to prevent damaging the rubber impeller when you slide it on. I also liberally grease the shaft first.

A little gasket sealant (the kind that stays flexible) on the gasket is a good idea if the mating surfaces aren't perfect. This water pump isn't high pressure at all so a perfect gasket seal is what you want but a good gasket seal will work.

 

[Douglasdzaster]

I would wire brush what I can reach with a small brush and not worry too much about the rest. Just verify that the passages are clear, running in salt water for years can close up those passages.

I'd also use fine (200 grit) emory paper on the shaft to prevent damaging the rubber impeller when you slide it on. I also liberally grease the shaft first.

A little gasket sealant (the kind that stays flexible) on the gasket is a good idea if the mating surfaces aren't perfect. This water pump isn't high pressure at all so a perfect gasket seal is what you want but a good gasket seal will work.

Thanks for the reply. I run it in freshwater. I bought the rig here locally and we’re about 3 hours from the salt. But some of the stuff I’ve found on the motor tells me it may have been used in saltwater. The trailer doesn’t have any corrosion. I’ll finish cleaning it up and I have some Permatex #3 aviator that brushes on and doesn’t harden. I’ll also take your advice on the Emory paper for the shaft. I’ve worked on a lot of engines in the past but this is my first outboard. Been fun though fixing up the boat the way I want it and getting the outboard running was a job. I had to learn about link and sync after rebuilding the carburetors. Broken bolt in the thermostat housing. All fun things. Thanks again for the help. Don’t know what I’d do without the forum. And everyone’s help. I’m very grateful.

 

[maintenanceguy]

since you mentioned a broken bolt...stainless hardware in aluminum tends to corrode. It's much worse in salt water but it's an issue either way. I always wire brush and coat all fastener threads with marine grease before reassembly. Anti-seize has copper in it which makes the corrosion worse so don't use that for marine fasteners. There is a marine anti-seize but I've never used it. Everything comes apart easier later if the threads were greased.

 

[Douglasdzaster]

since you mentioned a broken bolt...stainless hardware in aluminum tends to corrode. It's much worse in salt water but it's an issue either way. I always wire brush and coat all fastener threads with marine grease before reassembly. Anti-seize has copper in it which makes the corrosion worse so don't use that for marine fasteners. There is a marine anti-seize but I've never used it. Everything comes apart easier later if the threads were greased.

I actually have the marine anti seize. I has no metals in it. I removed the thermostat to check for debris and the bolts came right out. The motor itself has one spot where the paint flaked. I used fluid seal on the entire thing and have no corrosion and it looks almost new. I had to torque the exhaust plate and no bolts broke on it. I was surprised they were loose at all. Glad I checked them just for the sake of doing so. Thanks again for sharing your knowledge. You think the Permatex #3 aviation gasket sealant will be okay? I have the #2 also and it may seal a little better?

 

[MrGiggles]

Usually those old Suzukis and Yamahas will turn into a pile of white dust if they've been run in saltwater for any period of time. Been a lot of good running motors scrapped just because they could no longer be disassembled without adding hours of labor for broken bolts.

 

[Douglasdzaster]

Usually those old Suzukis and Yamahas will turn into a pile of white dust if they've been run in saltwater for any period of time. Been a lot of good running motors scrapped just because they could no longer be disassembled without adding hours of labor for broken bolts.

Maybe it wasn’t used in saltwater. I hope it last me awhile. I’ve done a lot to bring it back to life.That thermostat bolt was the only one that’s been bad so far. Carburetor bolts are in good shape. Carburetors them selfs were eat up because it had been sitting and ethanol did it’s worst. I replaced everything but the carburetor bodies. Took a machine shop to remove the seats and one of the jets someone had tried and rounded them off. Lu bolts good as well. I haven’t had to pull the head yet. I started to replace the head gaskets but the old ones don’t leak and compression is good. I’m going to keep looking for corrosion though. It’s been neglected maintenance wise and patched up to keep it running. I’ve fixed a lot of things that I looked at and said man that’s just wrong. Lol I’ll enjoy it as long as I can keep her going. Short shaft on a 1982 Monark 1652. Also my first tin boat. It’ll make the boat skip across the lake and I can get as shallow as I want when I put the trolling motor down. Places those big bass boats can’t get to. Lol

 

[wmk0002]

I wouldn't worry about pulling the driveshaft seal housing out unless you have water in the lower unit. The corrosion looks pretty light too. The lower unit on my Yamaha 30 has some light corrosion that looks somewhat similar, probably because it was run in brackish water in Louisiana. I bet lots of people who run in those areas don't both to flush their motors and as a result the corrosion build up on those few places where the water kinda pools and cant drain.

I actually have my lower unit off right now and had some water in it so I just replaced the leaking driveshaft seals. Holds pressure better but still falls off hard when I take it to 10 psi and then settles in on about 5-6 psi. Hard to tell if its the shift shaft boot or the driveshaft seals as the area around the shift shaft is filled with gunk and debris. For $30 more dollars I can reseal them both so I will definitely be doing that soon.

 

[Douglasdzaster]

Thanks for all the reply’s. I just came in out of the heat for a minute. I’ve cleaned up the lower housing and just gave it a final wipe after the acetone. Since it’s got some pits I have a decision to make. Permatex #3 aviation gasket sealant or Permatex #2. They both are none hardening but the #2 ( which I’ve never used) seems like a better sealant for this application. I’ve used the #3 a lot and it’s awesome. But I read it’s not the best for sealing aluminum surfaces where it has to fill in any spots. That one line from one person put the worry in my head.

 

[RaisedByWolves]

To remove that lower pump housing you have to disassemble the complete lower and remove the pinion from the drive shaft.

If you try and pry on that housing you will break it.

Ask me how I know.

 

[Douglasdzaster]

To remove that lower pump housing you have to disassemble the complete lower and remove the pinion from the drive shaft.

If you try and pry on that housing you will break it.

Ask me how I know.

Thanks for the reply and advice it’s greatly appreciated . This is my first outboard. The housing cleaned up good so I left well enough alone . I just came inside from completing the new water pump. Waiting on a gasket for the water tube pickup so I can get going again.

 

[Douglasdzaster]

Oh I went with the number 2 sealant. I’ll let y’all know if it works out. Now I’m waiting for one little washer on a slow boat from China so I can install the lower unit and get going again. The water keeps calling me but I’m stuck. Inspected the entire motor today. Fuel lines etc. Even pulled the thermostat and cleaned it up then checked at what temperature it opened and used a caliper to make sure it opened far enough for spec. Lol
Found more scaly looking stuff in the housing. Like a powder almost and I’m running in freshwater only. The lake I spend most of my time on is clear as can be. You can see several feet deep.I grabbed the water hose connected to the house to back flush since the lu was off. When I unscrewed the spray nozzle I noticed the nozzle was full of the stuff. It’s something in our water out here! With all the work I’ve done to the motor I’ve been running it quite a bit either in a tub or on muffs here. I’m going to ask the water company about this junk.
I’ll shut up now. Maybe clean my reels and organize my tackle.

 

[turbotodd]

Just to add, it doesn't take salt to corrode a motor. Brackish freshwater will do it too, just takes longer. And, I've seen improperly grounded boat houses--and improperly installed 110v chargers, etc installed on tin boats, and have seen the entire lower unit rot off, the hull gets pitted, in one case I got to the customer's boat house and could actually see tiny bubbles all around the boat (electrolysis). Just wanted to point this out as salt isn't the only killer to outboards. Yes grease on all threads if you ever want them to come back apart again!! I too have scrapped motors because the labor to remove parts with broken bolts exceeded the value of the running/working motor. Drilling stainless steel is a pain in the butt, labor intensive, eats drill bits and drill motors, and there are times when it's just impossible to get a broken bolt out, so you have to replace the component anyway.

 

[Douglasdzaster]

Just to add, it doesn't take salt to corrode a motor. Brackish freshwater will do it too, just takes longer. And, I've seen improperly grounded boat houses--and improperly installed 110v chargers, etc installed on tin boats, and have seen the entire lower unit rot off, the hull gets pitted, in one case I got to the customer's boat house and could actually see tiny bubbles all around the boat (electrolysis). Just wanted to point this out as salt isn't the only killer to outboards. Yes grease on all threads if you ever want them to come back apart again!! I too have scrapped motors because the labor to remove parts with broken bolts exceeded the value of the running/working motor. Drilling stainless steel is a pain in the butt, labor intensive, eats drill bits and drill motors, and there are times when it's just impossible to get a broken bolt out, so you have to replace the component anyway.

Wow some scary stuff. I’m about 3 hours or so from any salt. Pull start the motor. I never leave my trolling battery in the boat. Or the one I run my fish finder and lights with. They get charged on the bench in the shop. When I’m not using the boat it’s here in the driveway. I would like to change the head gaskets pretty soon since they look like the original with the motor paint still on them. I’ve noticed a wrinkle on the edge in one of the corners. Guess getting those bolts out will be the true test. Planning on all new bolts when I do decide to work up the courage. As for now the lower unit is still sitting on the bench with the new pump kit installed waiting for the parts to connect it to the water pickup tube. Which finally shipped from the vendor today.